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New Scientist
Change your diet and it may make you brighter
Do specific chemicals in your brain play a key role in how clever
you are? Brain imaging specialists in New
Mexico have found a link between variations in thelevels of two
brain chemicals and the results of IQ tests. It's
possible, they say, that changing the balance of the chemicals with
dietary supplements could give your
intelligence a boost.
Concentrations of the chemicals N-acetylaspartate (NAA) and choline
are known to change when people suffer
from brain diseases or injuries. But the new study reveals that in
healthy people, levels of the chemicals account
for a large amount of the variation in people's IQs.
NAA is found only in neurons and is thought to contribute to their
healthy function. Choline is present in nerve
cell membranes. When large numbers of neurons are injured or
killed, NAA levels drop and damaged cells
release more choline.
In patients with injured brains, this shift is linked to a loss of
cognitive function. But neuroscientist William
Brooks of the University of New Mexico in Albuquerque and his
colleagues wondered how the chemicals
fluctuate in people with normal, healthy brains. "We really didn't
know what to expect," says Brooks. "But we
were surprised by what we found."
From a local college, they selected 26 volunteers who had no
history of brain disease or psychiatric illnesses.
They then used a technique called magnetic resonance spectroscopy
to measure levels of NAA and choline in a
brain region involved in a wide variety of cognitive functions.
Within a week, the students were given standard
IQ tests.
The team found a strong link between levels of the chemicals and
their performance in the tests. Low levels of
choline and high levels of NAA were associated with high IQ.
Statistical analysis showed NAA and choline
levels together could account for 45 per cent of the variation in
the IQ tests. In comparison, the level of a brain
chemical called creatine showed no significant link to IQ
(Proceedings of the Royal Society B, vol 266, p
1375).
Brooks speculates that in healthy people, levels of NAA and choline
may indicate the rate at which neurons are
being damaged, and thus the amount of energy the brain is using up
to maintain them. "If you have healthy
neurons, but you're struggling to keep them repaired, it makes
sense you won't be as cognitively sound," he
says.
But there is another possible explanation, says Brooks: NAA and
choline might directly enhance and inhibit the
function of neurons. If that's true, Brooks says it might be
possible to improve intellectual performance by
manipulating the level of these compounds with dietary supplements.
Howard Gardner, a psychologist at Harvard University warns that
other supposed biochemical indicators of
intelligence have proved unreliable. And he adds that performance
in IQ tests can be affected by many factors,
such as the subject's health and their motivation. He suggests that
Brooks's images may in fact be tracking one
of these other factors. "Beware the intelligence equals IQ

equation," says Gardner.

Brooks agrees that his results are preliminary. He and his
colleagues hope to examine more carefully what types

of abilities NAA and choline best predict in a larger group of
volunteers.

###
Author: Philip Cohen
New Scientist issue 7th July 1999
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